The present invention relates to a retention device for a tubular casing material for receiving a viscous or granular filling material in a packaging machine, in particular a clipping machine.
The invention relates, in particular, to a retention device for a tubular casing material for receiving a viscous or granular filling material in a packaging machine, in particular in a clipping machine, and preferably, in a sausage clipping machine that has a filling tube for filling the tubular casing material with the filling material, such as sausage meat. The retention device, or casing brake, includes a first brake ring, which can be mounted coaxially on the filling tube, the inner diameter of said brake ring being larger than the outer diameter of the filling tube and on the inner circumference of which brake ring a first brake means is provided, along which the casing material or sausage casing can be guided in the filling direction of the filling material against a friction force acting upon the casing material.
The present invention also relates to a clipping machine for producing sausage-shaped products, in particular sausage products, from a viscous or granular filling material such as sausage meat, which can be filled into a tubular casing material, such as a sausage casing, the clipping machine comprising a filling tube for filling the tubular casing material with the filling material in the filling direction, a supply of casing material disposed on the filling tube and a retention device for applying a predetermined friction force that acts counter to the filling direction on the casing material, which can be drawn off in the filling direction.
It is known, in practice, that when producing sausage products, for example, the sausage meat is fed by a filling machine to a clipping machine via a filling tube of the closing and severing unit. In the clipping machine, the filling material is filled into a tubular casing material that is closed at one end by a first clip, and the tubular casing material is closed by placing a second clip. The resultant sausage product is then severed from the remaining supply of casing material, and the finished sausage product is carried out of the clipping machine.
When a filling material, which, besides sausage meat, can also be putty or sealing compound, for example, is fed through a filling tube coupled to a filling machine into a tubular casing closed at one end, a sausage-shaped product is formed at the filling tube exit. The casing, which was previously pulled from the supply of casing material onto the filling tube either manually or automatically, or which was simultaneously formed from a flat web of film folded and sealed around the filling tube to form a tube, is drawn off the filling tube by the filling pressure.
In known clipping machines, a brake ring or casing brake is disposed around the filling tube near the filling tube exit. This casing brake, which typically includes an annular rubber lip, is biased elastically against the filling tube, thus pressing the casing against the filling tube. This pressure generates a friction force that ensures that the casing material or sausage skin is drawn in a controlled manner during the filling process from the supply disposed on the filling tube and that, depending on the bias of the brake ring, a sausage with the desired fullness is produced.
Such a retention device or casing brake is known from German patent application 10 2005 044 879 (US 2007/0072528). The device has a support bracket that can be moved parallel to the filling tube axis. Into this support bracket, a brake ring can be inserted that fully encircles the filling tube and exerts a pressure on the casing material guided between the brake ring and the filling tube in order to generate a friction force. By means of a crank transmission, the brake ring can be moved via the support bracket in accordance with the filling operation together with the casing material for a certain length in the pull-off direction, or in the opposite direction to the pull-off direction. By displacing the brake ring in the direction opposite to the filling direction, a volume into which the filling material can escape is created, by means of which the production rate of the clipping machine when continuously filling the casing material can be further increased.
These known retention devices or casing brakes have certain disadvantages, however. For example, the friction force, which is initially set by selecting the brake ring, is constant during the following production process at least, and cannot be changed during the ongoing process, or only with substantial interruptions of the production process. When the casing material is changed, it is necessary, to achieve an identical friction force and hence an identical braking effect, either to replace the currently used brake ring with a brake ring having a different inner diameter or a different braking behavior, or to change, i.e., increase or decrease, the amount by which the brake ring is compressed. In either case, as already mentioned, the production process must be interrupted. Fine adjustment of the braking force is not possible, or only in a very time-consuming manner. It may likewise be necessary to change the brake ring when the filling pressure changes, or when the brake ring squeeze value changes.